U.S. patent application number 17/233752 was filed with the patent office on 2021-10-28 for method of monitoring an additive manufacturing process, additive manufacturing method, apparatus for monitoring an additive manufacturing process and additive manufacturing apparatus.
The applicant listed for this patent is MITSUBISHI HEAVY INDUSTRIES, LTD.. Invention is credited to Yasuyuki FUJIYA, Ryuichi NARITA, Thomas SEEFELD, Shuji TANIGAWA, Claus THOMY, Dieter TYRALLA.
Application Number | 20210331245 17/233752 |
Document ID | / |
Family ID | 1000005555828 |
Filed Date | 2021-10-28 |
United States Patent
Application |
20210331245 |
Kind Code |
A1 |
NARITA; Ryuichi ; et
al. |
October 28, 2021 |
METHOD OF MONITORING AN ADDITIVE MANUFACTURING PROCESS, ADDITIVE
MANUFACTURING METHOD, APPARATUS FOR MONITORING AN ADDITIVE
MANUFACTURING PROCESS AND ADDITIVE MANUFACTURING APPARATUS
Abstract
A method of monitoring an additive manufacturing process
according to at least one embodiment of the present disclosure
includes the steps of acquiring information on a temperature of a
region upstream of a melt pool in a scanning direction of an energy
beam, the melt pool being formed by irradiating a raw material with
the energy beam, acquiring a parameter indicating a cooling rate of
the region based on the information on the temperature, and
determining a formation status based on the parameter.
Inventors: |
NARITA; Ryuichi; (Tokyo,
JP) ; TANIGAWA; Shuji; (Tokyo, JP) ; FUJIYA;
Yasuyuki; (Tokyo, JP) ; THOMY; Claus; (Bremen,
DE) ; TYRALLA; Dieter; (Bremen, DE) ; SEEFELD;
Thomas; (Bremen, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
MITSUBISHI HEAVY INDUSTRIES, LTD. |
Tokyo |
|
JP |
|
|
Family ID: |
1000005555828 |
Appl. No.: |
17/233752 |
Filed: |
April 19, 2021 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B33Y 10/00 20141201;
B33Y 30/00 20141201; B22F 12/90 20210101; B33Y 50/02 20141201; B22F
2203/11 20130101; B22F 10/368 20210101; B22F 10/28 20210101; B22F
12/49 20210101; B22F 10/85 20210101 |
International
Class: |
B22F 10/368 20060101
B22F010/368; B22F 10/85 20060101 B22F010/85; B22F 12/49 20060101
B22F012/49; B22F 12/90 20060101 B22F012/90; B22F 10/28 20060101
B22F010/28; B33Y 10/00 20060101 B33Y010/00; B33Y 30/00 20060101
B33Y030/00; B33Y 50/02 20060101 B33Y050/02 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 27, 2020 |
JP |
2020-078740 |
Claims
1. A method of monitoring an additive manufacturing process,
comprising the steps of: (a) acquiring information on a temperature
of a region upstream of a melt pool in a scanning direction of an
energy beam, the melt pool being formed by irradiating a raw
material with the energy beam; (b) acquiring a parameter indicating
a cooling rate of the region based on the information on the
temperature; and (c) determining a formation state based on the
parameter.
2. The method of monitoring an additive manufacturing process
according to claim 1, wherein the information on the temperature
includes temperatures at the same time at at least two points that
are in different positions along the scanning direction in at least
the region.
3. The method of monitoring an additive manufacturing process
according to claim 1, wherein in the step (b) acquiring the
parameter, a difference in temperature with respect to a difference
in position in the scanning direction at a certain time is obtained
as the parameter, based on the information on the temperature.
4. The method of monitoring an additive manufacturing process
according to claim 3, further comprising a step of: (d) calculating
a cooling rate of the region based on the difference in temperature
and a scanning rate of the energy beam.
5. The method of monitoring an additive manufacturing process
according to claim 1, wherein the region is upstream in the
scanning direction of a position that has a temperature equal to a
melting point of the raw material.
6. The method of monitoring an additive manufacturing process
according to claim 1, wherein in the step (a) acquiring information
on the temperature, when the region includes a first region in
which the temperature monotonically decreases further upstream in
the scanning direction and a second region in which the temperature
does not monotonically decrease further upstream in the scanning
direction, information on the temperature of a third region is
acquired, the third region being a region in which the temperature
monotonically decreases further upstream in the scanning direction
upstream of the second region in the scanning direction.
7. The method of monitoring an additive manufacturing process
according to claim 6, wherein in the step (a) acquiring information
on the temperature, information on the temperature of a region
within the third region is acquired, where the region has a
temperature equal to or higher than a temperature that is lower
than the temperature of the second region by half the temperature
difference between the temperature of the second region and a room
temperature.
8. An additive manufacturing method, comprising the steps of: (e)
irradiating a raw material with an energy beam; and (f) determining
a formation state by using the method of monitoring an additive
manufacturing process of claim 1.
9. The additive manufacturing method according to claim 8, wherein
in the step (e) irradiating with the energy beam, when it is
determined that the formation status is defective in the step (f)
determining the formation status, irradiation of the energy beam is
suspended.
10. An apparatus for monitoring an additive manufacturing process,
comprising: an information acquisition unit configured to acquire
information on a temperature of a region upstream of a melt pool in
a scanning direction of an energy beam, the melt pool being formed
by irradiating a raw material with the energy beam; a parameter
acquisition unit configured to acquire a parameter indicating a
cooling rate of the region based on the information on the
temperature of the region; and a determination unit configured to
determine a formation status based on the parameter.
11. An additive manufacturing apparatus, comprising: an energy beam
irradiation unit capable of irradiating a raw material with an
energy beam; and the apparatus for monitoring an additive
manufacturing process of claim 10.
12. The additive manufacturing apparatus according to claim 11,
further comprising: a measurement optical system configured to
acquire information on the temperature, wherein the energy beam
irradiation unit includes a generation unit configured to generate
a light beam as the energy beam and an irradiation optical system
configured to irradiate the raw material with the light beam, and a
part of the measurement optical system is common to at least a part
of the irradiation optical system.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of priority to Japanese
Patent Application Number 2020-078740 filed on Apr. 27, 2020. The
entire contents of the above-identified application are hereby
incorporated by reference.
TECHNICAL FIELD
[0002] The disclosure relates to a method of monitoring an additive
manufacturing process, an additive manufacturing method, an
apparatus for monitoring an additive manufacturing process, and an
additive manufacturing apparatus.
RELATED ART
[0003] The additive manufacturing method for performing additive
manufacturing of three-dimensional objects is used as a
manufacturing method for various metal products. In manufacturing a
metal product by the additive manufacturing method, a metal powder
as a material is melted by an energy beam such as a laser beam and
then solidified to form a three-dimensional product (e.g., see JP
6405028 B).
SUMMARY
[0004] In the formation of a metal product by an additive
manufacturing method, the cooling rate of a bead formed by melting
metal powder with an energy beam is easily affected by the
temperature of a formed object around the bead. In addition, in the
formation of the metal product by the additive manufacturing
method, since the metal powder serving as the material is heated by
the energy beam as described above, heat easily accumulates in the
formed object. Therefore, in the formation of the metal product by
the additive manufacturing method, the cooling rate of the bead is
likely to change (decrease).
[0005] The cooling rate of the bead affects the state of the bead
fiber. Therefore, in order to keep the cooling rate of the bead
within an appropriate range, the additive manufacturing process is
preferably monitored based on information on the cooling rate of
the bead.
[0006] In view of the circumstances described above, an object of
at least one embodiment of the present disclosure is to monitor an
additive manufacturing process in additive manufacturing to
contribute to quality improvement of a formed object.
[0007] (1) A method of monitoring an additive manufacturing process
according to at least one embodiment of the present disclosure
includes the steps of, acquiring information on a temperature of a
region upstream of a melt pool in a scanning direction of an energy
beam, the melt pool being formed by irradiating a raw material with
the energy beam, acquiring a parameter indicating a cooling rate of
the region based on the information on the temperature, and
determining a formation status based on the parameter.
[0008] (2) An additive manufacturing method according to at least
one embodiment of the present disclosure includes the steps of
irradiating a raw material with an energy beam, and determining a
formation status by using the method of monitoring an additive
manufacturing process of the above method 1).
[0009] (3) An apparatus for monitoring an additive manufacturing
process according to at least one embodiment of the present
disclosure includes, an information acquisition unit configured to
acquire information on a temperature of a region upstream of a melt
pool in a scanning direction of an energy beam, the melt pool being
formed by irradiating a raw material with the energy beam, a
parameter acquisition unit configured to acquire a parameter
indicating a cooling rate of the region based on the information on
the temperature of the region, and a determination unit configured
to determine a formation status based on the parameter.
[0010] (4) An additive manufacturing apparatus according to at
least one embodiment of the present disclosure includes an energy
beam irradiation unit capable of irradiating a raw material with an
energy beam, and the apparatus for monitoring an additive
manufacturing process according to the above configuration (3).
[0011] According to at least one embodiment of the present
disclosure, it is possible to contribute to improve the quality of
a formed object in additive manufacturing.
BRIEF DESCRIPTION OF DRAWINGS
[0012] The disclosure will be described with reference to the
accompanying drawings, wherein like numbers reference like
elements.
[0013] FIG. 1 is a schematic diagram illustrating an overall
configuration of an additive manufacturing apparatus, as an
apparatus to which an additive manufacturing method according to at
least one embodiment of the present disclosure is applicable.
[0014] FIG. 2 is a schematic overall configuration diagram of a
light beam irradiation unit according to some embodiments.
[0015] FIG. 3 is a diagram illustrating an overall configuration of
an apparatus for monitoring an additive manufacturing process
included in the additive manufacturing apparatus according to some
embodiments.
[0016] FIG. 4 is a diagram schematically illustrating a temperature
distribution, of a melt pool on the powder bed and the region in
the vicinity thereof, measured during shaping by a thermometer
according to some embodiments.
[0017] FIG. 5 is an enlarged schematic view of a region where a
melt pool appears in the measurement region illustrated in FIG.
4.
[0018] FIG. 6 is a diagram for describing contents of processing in
a parameter acquisition unit.
[0019] FIG. 7 is a flowchart illustrating a processing procedure of
an additive manufacturing method when a formed object is formed by
an additive manufacturing apparatus including an apparatus for
monitoring according to some embodiments.
[0020] FIG. 8 is a flowchart illustrating a processing procedure of
a subroutine of a formation status determination step.
DESCRIPTION OF EMBODIMENTS
[0021] Hereinafter, some embodiments of the present disclosure will
be described with reference to the accompanying drawings. It is
intended, however, that dimensions, materials, shapes, relative
positions or the like of the components described in the
embodiments shall be interpreted as illustrative only and not
intended to limit the scope of the present disclosure.
[0022] For instance, an expression of relative or absolute
arrangement such as "in a direction", "along a direction",
"parallel", "orthogonal", "centered", "concentric" or "coaxial"
shall not be construed as indicating only the arrangement in a
strict literal sense, but also includes a state where the
arrangement is relatively displaced by a tolerance, or by an angle
or a distance within a range in which it is possible to achieve the
same function.
[0023] For instance, an expression of an equal state such as
"same", "equal", "uniform" or the like shall not be construed as
indicating only the state in which the feature is strictly equal,
but also includes a state in which there is a tolerance or a
difference within a range where it is possible to achieve the same
function.
[0024] Further, for instance, an expression of a shape such as a
rectangular shape, a cylindrical shape or the like shall not be
construed as only the geometrically strict shape, but also includes
a shape with unevenness, chamfered corners or the like within the
range in which the same effect can be achieved.
[0025] On the other hand, an expression such as "provided",
"comprise", "contain", "include", or "have" are not intended to be
exclusive of other components.
[0026] Additive Manufacturing Apparatus 1
[0027] FIG. 1 is a schematic diagram illustrating an overall
configuration of an additive manufacturing apparatus 1, as an
apparatus to which an additive manufacturing method according to at
least one embodiment of the present disclosure is applicable.
[0028] The additive manufacturing apparatus 1 is an apparatus for
manufacturing a three-dimensional formed object 15 by performing
additive manufacturing by irradiating a metal powder as a raw
material powder laid in layers with a light beam 65 as an energy
beam, and can perform additive manufacturing by a powder bed
method.
[0029] The additive manufacturing apparatus 1 illustrated in FIG. 1
can form, for example, a rotor blade or a stator vane of a turbine
such as a gas turbine or a steam turbine, or a component such as a
combustor basket, a transition pipe or a nozzle of a combustor.
[0030] The additive manufacturing apparatus 1 illustrated in FIG. 1
includes a storage unit 31 for raw material powder 30. The additive
manufacturing apparatus 1 illustrated in FIG. 1 includes a powder
bed forming unit 5 including a base plate 2 on which a powder bed 8
is formed by the raw material powder 30 supplied from the storage
unit 31. The additive manufacturing apparatus 1 illustrated in FIG.
1 includes an energy beam irradiation unit 9 (an example of an
irradiation unit) capable of irradiating the powder bed 8 with the
light beam 65 as an energy beam. In the following description, the
energy beam irradiation unit 9 is also referred to as a light beam
irradiation unit 9. The additive manufacturing apparatus 1
illustrated in FIG. 1 includes a control device 20 capable of
controlling a powder laying unit 10, a drive cylinder 2a of the
base plate 2, and the light beam irradiation unit 9, which will be
described later.
[0031] The base plate 2 serves as a base on which the formed object
15 is formed. The base plate 2 is disposed, inside a substantially
cylindrical cylinder 4 having a central axis extending in the
vertical direction, so as to be vertically movable by a drive
cylinder 2a. The powder bed 8 formed on the base plate 2 is newly
formed by laying powder on the upper layer side every time the base
plate 2 is lowered in each cycle during the shaping work.
[0032] The additive manufacturing apparatus 1 illustrated in FIG. 1
includes a powder laying unit 10 configured to lay the raw material
powder 30 on a base plate 2 to form the powder bed 8. The powder
laying unit 10 supplies the raw material powder 30 from the storage
unit 31 to the upper surface side of the base plate 2 and flattens
the surface of the raw material powder 30, thereby forming the
layered powder bed 8 having a substantially uniform thickness over
the entire upper surface of the base plate 2. The powder bed 8
formed in each cycle is selectively solidified by being irradiated
with the light beam 65 from the light beam irradiation unit 9, and
in the next cycle, the raw material powder 30 is laid again on the
upper layer side by the powder laying unit 10 to form a new powder
bed 8, whereby the powder beds 8 are stacked in layers.
[0033] The raw material powder 30 supplied from the powder laying
unit 10 is a powdery substance serving as a raw material of the
formed object 15. For example, a metal material such as iron,
copper, aluminum, or titanium, or a non-metal material such as
ceramic can be widely used.
[0034] The control device 20 illustrated in FIG. 1 is a control
unit of the additive manufacturing apparatus 1 illustrated in FIG.
1, and is composed of an electronic computation device such as a
computer, for example.
[0035] In the control device 20 illustrated in FIG. 1, information
on the shape of the formed object 15, that is, the dimensions of
each part, which is necessary for shaping the formed object 15, is
input. Information on dimensions or the like of each part necessary
for shaping the formed object 15 may be input from, for example, an
external device and stored in, for example, a storage unit (not
illustrated) of the control device 20. Details of control contents
in the control device 20 will be described later.
[0036] Light Beam Irradiation Unit 9
[0037] FIG. 2 is a schematic overall configuration diagram of the
light beam irradiation unit 9 according to some embodiments. The
light beam irradiation unit 9 according to some embodiments
includes an oscillation device 91 that outputs the light beam 65, a
scanning device 93 that scans the light beam 65, a beam splitter
95, and a thermometer 97.
[0038] In the light beam irradiation unit 9 according to some
embodiments, the oscillation device 91 is a light beam generation
unit (an example of a generation unit) that generates a light beam
as an energy beam, and outputs the light beam 65 based on a control
signal from the control device 20. For example, when the control
signal from the control device 20 includes information on the
output of the light beam 65, the oscillation device 91 outputs
(emits) the light beam 65 at an output corresponding to the
information.
[0039] In the following description, the scanning direction of the
light beam 65 is also simply referred to as a scanning direction.
Further, along the scanning direction, a direction in which the
light beam 65 travels, is defined as a downstream in the scanning
direction, and a side opposite to the downstream in the scanning
direction along the scanning direction is defined as an upstream in
the scanning direction.
[0040] In the light beam irradiation unit 9 according to some
embodiments, the scanning device 93 includes a mirror 931 for
scanning the light beam 65 from the oscillation device 91 and a
scanning optical system 930 including a lens (not illustrated) or
the like. The scanning device 93 is configured to irradiate the
powder bed 8 with the light beam 65 from the oscillation device 91
while scanning the light beam 65 based on a control signal from the
control device 20.
[0041] The light beam irradiation unit 9 according to some
embodiments includes an irradiation optical system 900 configured
to irradiate the raw material powder 30 with the light beam 65. The
irradiation optical system 900 according to some embodiments
includes the scanning optical system 930.
[0042] The light beam irradiation unit 9 according to some
embodiments includes an information acquisition unit 50 configured
to acquire information on the temperature of a region upstream of
the melt pool in the scanning direction as described later. The
information acquisition unit 50 includes the thermometer 97
configured to measure the temperature of a melt pool 81 on the
powder bed 8 and the region in the vicinity thereof, and a
measurement optical system 53 configured to guide radiation light
(thermal radiation) from the melt pool on the powder bed 8 and the
region in the vicinity thereof to the radiation thermometer 97.
[0043] The thermometer 97 may be, for example, a radiation
thermometer. In the following description, it is assumed that the
thermometer 97 is a two-color thermometer and includes a detection
element 97a for detecting temperature.
[0044] In the light beam irradiation unit 9 according to some
embodiments, the radiation light from the melt pool on the powder
bed 8 and the region in the vicinity thereof is incident on the
beam splitter 95 through the scanning mirror 931 or the like of the
scanning device 93. The radiation light incident on the beam
splitter 95 is reflected by the beam splitter 95 and is incident on
the thermometer 97. That is, in the light beam irradiation unit 9
according to some embodiments, the measurement optical system 53
includes the beam splitter 95 and the components of the irradiation
optical system 900 that are disposed closer to the powder bed 8
than the beam splitter 95 along the optical path of the light beam
65, such as the scanning mirror 931. In the light beam irradiation
unit 9 according to some embodiments, a part of the measurement
optical system 53 is common to at least a part of the irradiation
optical system 900.
[0045] In the formation of a metal product by the additive
manufacturing method, the cooling rate of a bead formed by melting
metal powder with an energy beam is easily affected by the
temperature of a formed object around the bead. In addition, in the
formation of the metal product by the additive manufacturing
method, since the metal powder as the material is heated by the
energy beam as described above, heat is easily accumulated in the
formed object. Therefore, in the formation of the metal product by
the additive manufacturing method, the cooling rate of the bead is
likely to change (decrease).
[0046] The cooling rate of the bead affects the state of the bead
fiber. Therefore, in order to keep the cooling rate of the bead
within an appropriate range, the additive manufacturing process is
preferably monitored based on information on the cooling rate of
the bead.
[0047] Therefore, in the additive manufacturing apparatus 1
according to some embodiments, as described below, the additive
manufacturing process is monitored on the basis of information on
the cooling rate of the bead upstream of the melt pool 81 in the
scanning direction.
[0048] FIG. 3 is a diagram illustrating an overall configuration of
an apparatus for monitoring an additive manufacturing process
included in the additive manufacturing apparatus 1 according to
some embodiments. The monitoring apparatus 100 illustrated in FIG.
3 includes the above-described information acquisition unit 50, a
parameter acquisition unit 110, and a formation status
determination unit 120 (an example of a determination unit).
Information Acquisition Unit 50
[0049] In the monitoring apparatus 100 illustrated in FIG. 3, the
information acquisition unit 50 includes the thermometer 97 and the
measurement optical system 53 as described above.
[0050] In some embodiments, the thermometer 97 and the measurement
optical system 53 are configured to be capable of measuring the
temperature of the melt pool 81 on the powder bed 8 and the region
in the vicinity thereof.
[0051] FIG. 4 is a diagram schematically illustrating a temperature
distribution, of the melt pool 81 on the powder bed 8 and the
region in the vicinity thereof, measured during shaping by a
thermometer 97 according to some embodiments. The thermometer 97
according to some embodiments is configured to be able to
simultaneously measure the temperature in the measurement region
511 as illustrated in FIG. 4. That is, information of the
temperature distribution (temperature distribution information) 513
illustrated in FIG. 4 is the information on the temperature
distribution in the measurement region 511 at a certain time.
[0052] FIG. 5 is an enlarged schematic view of a region where the
melt pool 81 appears in the measurement region 511 illustrated in
FIG. 4. In FIG. 5, a range surrounded by a two-dot chain line is a
region corresponding to the melt pool 81. In addition, in FIG. 5, a
range sandwiched by two-dot chain lines from the left-right
direction in the drawing is a region corresponding to a formed bead
83.
[0053] The thermometer 97 according to some embodiments acquires
the temperature distribution information 513 which is the
information (temperature information) on the temperature of the
region 85 upstream of the melt pool 81 in the scanning direction.
For convenience of description, in the following description, the
region 85 is also referred to as an upstream region 85.
[0054] As described above, in some embodiments, the measurement
optical system 53 is configured to cause the radiation light from
the melt pool 81 on the powder bed 8 and the region in the vicinity
thereof to be incident on the thermometer 97 through the scanning
mirror 931 or the like of the scanning device 93 and the beam
splitter 95. Therefore, the measurement region 511 of the
thermometer 97 moves on the powder bed 8 along with the scanning of
the light beam 65. Therefore, the position of the melt pool 81
appearing in the measurement region 511 of the thermometer 97 does
not deviate from the measurement region 511 although there is some
variation due to the influence of the optical path length which
differs depending on the scanning position. Therefore, in the
thermometer 97 according to some embodiments is not required to
simultaneously measure the temperature of the entire upper surface
of the powder bed 8, and is only required to measure the
temperature of a limited range including the melt pool 81. In this
way, by limiting the measurement region 511 of the thermometer 97
not to the entire upper surface of the powder bed 8 but to the
region of the melt pool 81 on the powder bed 8 and the region in
the vicinity thereof, it is possible to reduce the load of the
processing described later in the parameter acquisition unit 110.
Accordingly, it is possible to suppress a delay in processing when
processing described later in the parameter acquisition unit 110 is
performed in real time during additive manufacturing.
[0055] Parameter Acquisition Unit 110
[0056] In the monitoring apparatus 100 illustrated in FIG. 3, the
parameter acquisition unit 110 is one of functional blocks realized
by a program executed by an electronic computation device (not
illustrated) of the control device 20.
[0057] In some embodiments, the parameter acquisition unit 110 is
configured to acquire a parameter (cooling rate parameter) P
indicating the cooling rate of the upstream region 85 on the basis
of information on the temperature of the upstream region 85. The
contents of the processing in the parameter acquisition unit 110
will be described below.
[0058] FIG. 6 is a diagram for describing contents of processing in
the parameter acquisition unit 110, and is a diagram illustrating
the temperature distribution information 513 illustrated in FIG. 5
and a graph 515 illustrating a relationship between a position and
a temperature along the scanning direction that are extracted from
the temperature distribution information 513.
[0059] The parameter acquisition unit 110 specifies a region Rtmax
having the highest temperature and the scanning direction in the
temperature distribution information 513 acquired by the
information acquisition unit 50. Then, the parameter acquisition
unit 110 extracts the temperature on the line segment L passing
through the region Rtmax having the highest temperature and
extending in the scanning direction in the temperature distribution
information 513. A graph 515 in FIG. 6 is a graph illustrating the
temperature extracted in this manner.
[0060] In the graph 515 of FIG. 6, the horizontal axis represents
the position along the direction corresponding to the scanning
direction on the detection element 97a of the thermometer 97 by,
for example, the number of pixels of the detection element 97a. The
vertical axis represents the temperature measured at each position
along the direction corresponding to the scanning direction on the
detection element 97a.
[0061] Since the temperature exceeding the measurement upper limit
temperature Tmax of the thermometer 97 cannot be measured, even
when the actual temperature exceeds the measurement upper limit
temperature Tmax of the thermometer 97, the actual temperature is
illustrated as the measurement upper limit temperature Tmax in the
graph 515 of FIG. 6.
[0062] Next, based on the graph 515 of FIG. 6, the parameter
acquisition unit 110 obtains, as a cooling rate parameter P, a
temperature difference .DELTA.T with respect to a position
difference .DELTA.x in the scanning direction at a certain time
t.
[0063] The temperature difference .DELTA.T with respect to the
position difference .DELTA.x in the scanning direction at a certain
time t is the temperature difference .DELTA.T with respect to the
position difference .DELTA.x in the scanning direction on the
powder bed 8, and can be obtained as follows, for example.
[0064] For example, in the graph 515 of FIG. 6, in the scanning
direction, downstream of the region Rtmax at which the temperature
is highest, the position, on the detection element 97a, at which
the temperature T1 immediately below the melting point Tm is
detected is defined as the position x1, and the position, on the
detection element 97a, at which the temperature T2 lower than the
temperature T1 is detected is defined as the position x2.
[0065] The temperature T2 is a temperature in the region where the
temperature decreases at a substantially constant rate from the
temperature T1.
[0066] In some embodiments, the parameter acquisition unit 110
obtains the temperature difference .DELTA.T with respect to the
position difference .DELTA.x in the scanning direction at a certain
time t as the change amount in temperature per pixel on the
detection element 97a, .DELTA.T'/.DELTA.x'.
[0067] The change amount in temperature per pixel on the detection
element 97a, .DELTA.T'/.DELTA.x', is expressed by the following
equation (1).
.DELTA.T'/.DELTA.x'[.degree. C./pixel]=(T2-T1)/(|x1-x2|) (1)
[0068] Here, |x1-x2| is the number of pixels between the position
x1 and the position x2 on the detection element 97a.
[0069] When the scanning rate Vs is constant and known in advance,
a cooling rate Vc can be obtained from the change amount in
temperature per pixel on the detection element 97a,
.DELTA.T'/.DELTA.x'. The procedure for obtaining the cooling rate
Vc will be described later.
Formation Status Determination Unit 120
[0070] In the monitoring apparatus 100 illustrated in FIG. 3, the
formation status determination unit 120 is one of functional blocks
realized by a program executed by an electronic computation device
(not illustrated) of the control device 20.
[0071] In some embodiments, the formation status determination unit
120 is configured to determine the formation status based on the
cooling rate parameter P acquired by the parameter acquisition unit
110. Hereinafter, contents of processing in the formation status
determination unit 120 will be described.
[0072] The formation status determination unit 120 calculates the
cooling rate Vc of the upstream region 85 as follows based on, the
temperature difference .DELTA.T with respect to the position
difference .DELTA.x in the scanning direction at a certain time t,
which has been obtained as the cooling rate parameter P, that is,
the above-described change amount .DELTA.T'/.DELTA.x', and the
scanning rate Vs of the light beam 65.
[0073] Let c (pixels/mm) be a coefficient that represents the
number of pixels on the detection element 97a to which the length
of 1 mm along the scanning direction on the powder bed 8
corresponds. Let Vs (mm/sec) be a scanning rate.
[0074] In this case, the cooling rate Vc can be obtained by
multiplying .DELTA.T'/.DELTA.x' (the change amount in temperature
per pixel on the detection element 97a) by the above coefficient c
and the scanning rate Vs, as expressed by the following equation
(2).
Vc[.degree. C./sec]={(t2-t1)/(|x1-x2|)}.times.c.times.Vs (2)
[0075] Thus, according to some embodiments, the cooling rate Vc of
the upstream region 85 can be calculated when the scanning rate is
constant and known in advance.
[0076] The formation status determination unit 120 compares the
cooling rate Vc obtained as described above with a threshold value
Vth of the cooling rate stored in advance in a storage device (not
illustrated).
[0077] For example, when the cooling rate Vc obtained as described
above is equal to or higher than the threshold value Vth, the
formation status determination unit 120 determines that the
formation status is favorable judging that the cooling rate Vc is
maintained within an appropriate range from the viewpoint of
maintaining the state of the fiber of the bead 83 in a desired
state.
[0078] For example, when the cooling rate Vc obtained as described
above is less than the threshold value Vth, the formation status
determination unit 120 determines that the formation status is
defective judging that the cooling rate Vc is deviated from an
appropriate range from the viewpoint of maintaining the state of
the fiber of the bead 83 in a desired state.
[0079] As described above, in some embodiments, the formation
status determination unit 120 determines whether the cooling rate
Vc is within the management range based on the temperature
distribution upstream of the melt pool 81 in the scanning
direction.
[0080] Since it is sufficient that the cooling rate Vc described
above can be obtained, the temperature information may include
temperatures at at least two points having different positions in
the scanning direction.
[0081] In the monitoring apparatus 100 illustrated in FIG. 3, when
the formation status determination unit 120 determines that the
formation status is favorable, the control device 20 controls each
unit of the additive manufacturing apparatus 1 to continue the
shaping.
[0082] In the monitoring apparatus 100 illustrated in FIG. 3, when
the formation status determination unit 120 determines that the
formation status is defective, the control device 20 controls each
unit of the additive manufacturing apparatus 1 so as to suspend
shaping, that is, irradiation of the light beam 65, until the
temperature of the formed object 15 decreases to a predetermined
temperature.
[0083] In the monitoring apparatus 100 illustrated in FIG. 3, when
the formation status determination unit 120 determines that the
formation status is defective, the control device 20 may control
each unit of the additive manufacturing apparatus 1 so as to
suspend shaping, that is, the irradiation of the light beam 65,
until a predetermined standby time elapses.
Temperature Range Suitable for Acquisition of Cooling Rate
Parameter P
[0084] The range of the upstream region 85 for acquiring the
cooling rate parameter P may be upstream in the scanning direction
of the position where the temperature is equal to the melting point
Tm of the raw material.
[0085] Accordingly, the cooling rate parameter P in the temperature
region that affects the state of the fiber can be obtained, and the
state of the fiber can be determined based on the cooling rate
parameter P.
[0086] In the graph 515 of FIG. 6, when the upstream region 85
includes the first region 521 in which the temperature
monotonically decreases toward upstream in the scanning direction
and the second region 522 in which the temperature does not
monotonically decrease toward upstream in the scanning direction,
the parameter acquisition unit 110 may acquire information on the
temperature of the third region 523 in which the temperature
monotonically decreases toward upstream in the scanning direction,
in the upstream of the second region 522 in the scanning
direction.
[0087] In the case where the raw material powder 30 is a pure metal
powder, when the raw material powder 30 heated and melted by the
light beam 65 is cooled and solidified, the temperature
monotonically decreases with time until the temperature reaches the
melting point Tm. When the temperature decreases to the melting
point Tm, a phenomenon in which the temperature hardly changes with
time, that is, the temperature does not monotonically decrease with
time, appears. After that, the temperature monotonically decreases
again.
[0088] Further, in the case where the raw material powder 30 is an
alloy, when the raw material powder 30 heated and melted by the
light beam 65 is cooled and solidified, the temperature
monotonically decreases with time until the temperature reaches the
melting point Tm as in the case where the raw material is a pure
metal. When the temperature decreases to the melting point, a
phenomenon in which the temperature slightly increases or decreases
with time, that is, a phenomenon in which the temperature does not
monotonically decrease with time appears. Thereafter, as in the
case where the raw material powder 30 is pure metal, the
temperature monotonically decreases again.
[0089] Therefore, the temperature of the second region 522 is
around the melting point Tm. Further, the temperature of the third
region 523 is lower than the melting point Tm, and the cooling rate
in the third region 523, particularly the cooling rate Vc in a
temperature region relatively close to the melting point Tm,
affects the state of the fiber of the bead 83.
[0090] Therefore, the parameter acquisition unit 110 can acquire
the temperature information on the temperature lower than the
melting point Tm, that is, the temperature information in the
temperature region where the cooling rate Vc affects the state of
the fiber of the bead 83 by acquiring the information on the
temperature of the third region 523. Thus, it is possible to
calculate the cooling rate suitable for grasping the state of the
fiber of the bead 83. Therefore, the state of the fiber of the bead
83 can be accurately grasped.
[0091] In addition, in the graph 515 of FIG. 6, the parameter
acquisition unit 110 may acquire information on the temperature of
a region, within the third region 523, which has a temperature
equal to or higher than a temperature that is lower than the
temperature of the second region 522 by half the temperature
difference between the temperature of the second region 522 and a
room temperature Tr.
[0092] In the third region 523, a temperature Tu that is lower than
the temperature (.apprxeq.Tm) of the second region 522 by a
temperature {(Tm-Tr)/2} that is one half of the temperature
difference between the temperature (.apprxeq.Tm) of the second
region 522 and the room temperature Tr may be set as a lower limit.
Then information on the temperature of a region having a
temperature equal to or higher than the temperature Tu may be
acquired.
[0093] This makes it possible to acquire information on the
temperature of a region, within the third region 523, which has a
temperature relatively close to the melting point Tm in particular.
Accordingly, it is possible to more accurately grasp the state of
the fiber of the bead 83.
Flowchart
[0094] FIG. 7 is a flowchart illustrating a processing procedure of
an additive manufacturing method when the additive manufacturing
apparatus 1 including the monitoring apparatus 100 according to
some embodiments described above shapes the formed object 15.
[0095] The additive manufacturing method according to some
embodiments illustrated in FIG. 7 includes an application condition
setting step S10, a powder bed forming step S20, an irradiation
step S30, and a formation status determination step S40. The
additive manufacturing method according to some embodiments
illustrated in FIG. 7 includes an irradiation stop step S70 and a
cooling waiting step S80.
Application Condition Setting Step S10
[0096] The application condition setting step S10 is a step for
setting information necessary for shaping the formed object 15. In
the application condition setting step S10, as described above,
information necessary for shaping the formed object 15, which are
the shape of the formed object 15, that is, the dimensions of each
part, is input to the control device 20, and is stored in the
storage unit (not illustrated). Information on dimensions or the
like of each part necessary for shaping the formed object 15 may be
input from, for example, an external device and stored in, for
example, a storage unit (not illustrated) of the control device 20.
Additionally, the operator may input necessary information by
operating an input device (not illustrated).
[0097] Here, the information input to the control device 20
includes, in addition to the above-described information,
information on the output of the light beam 65, the scanning rate
Vs, or the like, the value of the above-described coefficient c,
information of a temperature range related to acquisition of
information on the temperature based on the composition of the raw
material powder 30, or the like.
Powder Bed Forming Step S20
[0098] The powder bed forming step S20 is a step of forming the
powder bed 8 by supplying the raw material powder 30. That is, the
powder bed forming step S20 is a step of supplying the raw material
powder 30 from the storage unit 31 to the powder bed 8 and
laminating the raw material powder 30 by a prescribed
thickness.
[0099] To be specific, the control device 20 according to some
embodiments controls the drive cylinder 2a so that the base plate 2
is lowered by a lowering amount equal to the above-described
prescribed thickness.
[0100] Next, the control device 20 according to some embodiments
controls the powder laying unit 10 so as to supply the raw material
powder 30 to the upper surface side of the base plate 2.
[0101] By performing the powder bed forming step S20, a layer of
the raw material powder 30 laminated by a prescribed thickness is
formed on the upper portion of the powder bed 8.
Irradiation Step S30
[0102] The irradiation step S30 is a step of irradiating the raw
material powder 30 forming the powder bed 8 with the light beam
65.
[0103] Specifically, the control device 20 according to some
embodiments controls the light beam irradiation unit 9 to irradiate
the powder bed 8 with the light beam 65 while scanning the powder
bed 8 with the light beam 65.
[0104] That is, in the irradiation step S30, the raw material
powder 30 on the powder bed 8, which is laminated by the prescribed
thickness as described above, is irradiated with the light beam 65
while the light beam 65 is scanning, and is melted and solidified,
thereby shaping a part of the formed object 15.
[0105] More specifically, the control device 20 according to some
embodiments controls the light beam irradiation unit 9 to perform
irradiation while scanning the light beam 65 at a predetermined
output of the light beam 65 and a predetermined scanning rate.
[0106] By performing the irradiation step S30, a part of the formed
object 15 is newly formed on the upper portion of the powder bed 8
by a thickness corresponding to the prescribed thickness.
Formation Status Determination Step S40
[0107] The formation status determination step S40 is a step of
calculating the cooling rate parameter P described above and
determining the quality of the formation status based on the
calculated cooling rate parameter P. In the formation status
determination step S40, the quality of the formation status is
determined by executing a subroutine illustrated in FIG. 8.
[0108] FIG. 8 is a flowchart illustrating a processing procedure of
the subroutine of the formation status determination step S40.
[0109] The subroutine of the formation status determination step
S40 includes a temperature information acquisition step S41, a
cooling rate parameter acquisition step S43, and a formation status
determination step S45.
Temperature Information Acquisition Step S41
[0110] The temperature information acquisition step S41 is a step
of acquiring temperature distribution information 513 that is
information (temperature information) on the temperature of the
region 85 upstream of the melt pool 81 in the scanning direction.
In the temperature information acquisition step S41, the
thermometer 97 acquires the temperature distribution information
513 in the upstream region 85 as described above.
Cooling Rate Parameter Acquisition Step S43
[0111] The cooling rate parameter acquisition step S43 is a step of
acquiring a parameter (cooling rate parameter) P indicating the
cooling rate of the upstream region 85, based on the temperature
distribution information 513 that is information (temperature
information) on the temperature of the upstream region 85. In the
cooling rate parameter acquisition step S43, the parameter
acquisition unit 110 acquires the cooling rate parameter P as
described above.
Formation Status Determination Step S45
[0112] The formation status determination step S45 is a step of
determining the formation status based on the cooling rate
parameter P. In the formation status determination step S45, the
formation status determination unit 120 calculates the cooling rate
Vc of the upstream region 85 based on the cooling rate parameter P,
for example, as described above. That is, the preceding stage of
the formation status determination step S45 is a step of
calculating the cooling rate Vc of the upstream region 85.
[0113] Then, in the formation status determination step S45, for
example, when the calculated cooling rate Vc is equal to or higher
than the threshold value Vth, the formation status determination
unit 120 determines that the formation status is favorable judging
that the cooling rate Vc is maintained within an appropriate range
from the viewpoint of maintaining the state of the fiber of the
bead 83 in a desired state.
[0114] For example, in the formation status determination step S45,
when the calculated cooling rate Vc is less than the threshold
value Vth, the formation status determination unit 120 determines
that the formation status is defective judging that the cooling
rate Vc is deviated from an appropriate range from the viewpoint of
maintaining the state of the fiber of the bead 83 in a desired
state.
[0115] When it is determined that the formation status is favorable
in the formation status determination step S45, the step S50 is
affirmatively determined, and the process proceeds to the step
S60.
[0116] In the step S60, the control device 20 determines whether
the additive manufacturing is completed.
[0117] When the additive manufacturing is completed, the processing
in thi s flowchart ends.
[0118] When the additive manufacturing is not completed, the
control device 20 returns to the powder bed forming step S20 and
controls each unit so that the raw material powder 30 is laminated
by a prescribed thickness.
Irradiation Stop Step S70
[0119] When it is determined that the formation status is defective
in the formation status determination step S45, the step S50 is
negatively determined, and the process proceeds to the irradiation
stop step S70.
[0120] The irradiation stop step S70 is a step of stopping the
irradiation of the light beam 65. In the irradiation stop step S70,
the control device 20 controls each unit of the additive
manufacturing apparatus 1 such as outputting a control signal to
the oscillation device 91 of the light beam irradiation unit 9 so
as to suspend the irradiation of the light beam 65.
Cooling Waiting Step S80
[0121] The cooling waiting step S80 is a step of waiting for the
temperature of the formed object 15 to decrease, after the
irradiation of the light beam 65 is stopped in the irradiation stop
step S70. In the cooling waiting step S80, the control device 20
controls each unit of the additive manufacturing apparatus 1 so as
to wait until the temperature of the formed object 15 measured by,
for example, the thermometer 97 decreases to a predetermined
temperature. For example, when the control device 20 determines
that the temperature of the formed object 15 measured by, for
example, the thermometer 97 is equal to or lower than a
predetermined temperature, the process proceeds to step S60, and
the control device 20 determines whether the additive manufacturing
is completed.
[0122] As described above, in the cooling waiting step S80, the
control device 20 may control each unit of the additive
manufacturing apparatus 1 to wait until a predetermined standby
time elapses, for example. In this case, the control device 20
proceeds to the step S60 after a predetermined standby time, and
determines whether the additive manufacturing is completed.
[0123] The present disclosure is not limited to the above-described
embodiments, and includes embodiments obtained by modifying the
above-described embodiments and embodiments obtained by
appropriately combining these embodiments.
[0124] For example, the additive manufacturing process monitoring
method according to some embodiments described above has been
described as an application example in a case where the additive
manufacturing method by the powder bed method is performed.
However, the additive manufacturing process monitoring method is
also applicable to an additive manufacturing method by direct
energy deposition (DED).
[0125] In the method of monitoring an additive manufacturing
process according to some embodiments described above, the cooling
rate parameter P is obtained as the change amount in temperature
per pixel on the detection element 97a, .DELTA.T'/.DELTA.x', and
the cooling rate Vc is obtained from the change amount
.DELTA.T'/.DELTA.x'. Then, the obtained cooling rate Vc is compared
with a predetermined cooling rate threshold value Vth to determine
the quality of the formation status.
[0126] However, for example, the quality of the formation status
may be determined without obtaining the cooling rate Vc.
Specifically, for example, the quality of the formation status may
be determined by comparing the change amount obtained as the
cooling rate parameter P, .DELTA.T'/.DELTA.x' with a predetermined
threshold value Ath for the change amount. The threshold value Ath
in this case is the change amount in temperature per pixel,
.DELTA.Tth'/.DELTA.x', which corresponds to the threshold value Vth
of the cooling rate.
[0127] In some embodiments described above, although not
particularly specified, in the light beam irradiation unit 9
illustrated in FIG. 2, the oscillation device 91 is configured to
output the light beam 65 having an intensity distribution of a
TEMoo mode called, for example, a Gaussian beam. However, for
example, in the case of using a raw material powder 30 which is
suitable to be applied at a low cooling rate, the light beam 65
output from the oscillation device 91 may be converted into, for
example, a light beam having a high-order mode of a second order or
more, a top hat-formed intensity distribution, or the like by a
conversion device. Accordingly, the intensity distribution of the
light beam 65 on the powder bed 8 is changed, and the light beam 65
is irradiated in a wider range. Therefore, the formed object 15 is
likely to be warmed, and the cooling rate is decreased.
[0128] However, even in this case, it is preferable to determine
whether the cooling rate Vc is within the management range as
described above.
[0129] The contents described in the above embodiments are
understood as follows, for example.
[0130] (1) A method of monitoring an additive manufacturing process
according to at least one embodiment of the present disclosure
includes the steps of, acquiring information on a temperature of a
region (upstream region 85) upstream, in a scanning direction of a
light beam 65, of a melt pool 81 that is formed by irradiating a
raw material (raw material powder 30) with the light beam 65 as an
energy beam (temperature information acquisition step S41),
acquiring a parameter (cooling rate parameter) P indicating a
cooling rate Vc of the upstream region 85 based on the information
on the temperature (cooling rate parameter acquisition step S43),
and determining a formation status based on the cooling rate
parameter P (formation status determination step S45).
[0131] According to the above method (1), the temperature
information of the upstream region 85 is acquired, and the cooling
rate parameter P indicating the cooling rate Vc of the upstream
region 85 is acquired based on the temperature information of the
upstream region 85. Therefore, information necessary for
maintaining the cooling rate Vc of the bead 83 within an
appropriate range is obtained. Then, in the formation status
determination step S45, the quality of the formation status can be
determined based on the cooling rate parameter P. This contributes
to improving the quality of the formed object 15 in additive
manufacturing.
[0132] (2) In some embodiments, in the above method (1), the above
information on the temperature may include temperatures at the same
time at at least two points that are in different positions along
the scanning direction in at least the upstream region 85.
[0133] According to the above method (2), since it is not necessary
to obtain information at different times, it is possible to shorten
the time required for obtaining the cooling rate parameter P
indicating the cooling rate Vc of the upstream region 85.
[0134] Thus, the formation status can be quickly determined.
[0135] (3) In some embodiments, in the above method (1) or (2), in
the cooling rate parameter acquisition step S43, a temperature
difference .DELTA.T with respect to a position difference .DELTA.x
in the scanning direction at a certain time t is obtained as the
cooling rate parameter P, based on the above information on the
temperature.
[0136] According to the above method (3), the cooling rate
parameter P indicating the cooling rate Vc of the upstream region
85 is acquired by obtaining the temperature difference .DELTA.T
with respect to the position difference .DELTA.x in the scanning
direction at the certain time t.
[0137] (4) In some embodiments, the above method (3) further
includes a step (preceding stage of the formation status
determination step S45) of calculating a cooling rate Vc of the
upstream region 85 based on the temperature difference .DELTA.T and
a scanning rate Vs of the light beam 65.
[0138] As described above, when the scanning rate Vs is constant
and known in advance, the time required for the temperature to
decrease by the temperature difference .DELTA.T can be obtained
from the position difference .DELTA.x in the scanning direction at
a certain time t. That is, according to the above method (4), when
the scanning rate Vs is constant and known in advance, the cooling
rate Vc of the upstream region 85 can be calculated.
[0139] (5) In some embodiments, in any one of the above methods (1)
to (4), the upstream region 85 is upstream in the scanning
direction of a position that has a temperature equal to a melting
point Tm of the raw material.
[0140] According to the above method (5), it is possible to acquire
a parameter indicating the cooling rate Vc in a temperature region
that affects the state of the fiber. Thus, the state of the fiber
can be determined based on the parameter.
[0141] (6) In some embodiments, in any one of the above methods (1)
to (5), in the temperature information acquisition step S41, when
the upstream region 85 includes a first region 521 in which the
temperature monotonically decreases toward upstream in the scanning
direction and a second region 522 in which the temperature does not
monotonically decrease toward upstream in the scanning direction
information on the temperature of a third region 523, in which the
temperature monotonically decreases toward upstream in the scanning
direction in the upstream of the second region 522 in the scanning
direction, is acquired.
[0142] According to the above method (6), in the temperature
information acquisition step S41, the information on the
temperature lower than the melting point Tm, that is, the
temperature information in the temperature region where the cooling
rate Vc affects the state of the fiber of the bead 83 can be
acquired. Thus, the state of the fiber of the bead can be
accurately grasped.
[0143] (7) In some embodiments, in the above method (6), in the
temperature information acquisition step S41, within the third
region 523, information on the temperature of a region, in which
the temperature is equal to or higher than a temperature that is
lower than the temperature of the second region 522 by half the
temperature difference between the temperature of the second region
522 and a room temperature Tr, is acquired.
[0144] According to the above method (7), within the third region
523, by setting, as a lower limit, a temperature Tu that is lower
than the temperature of the second region 522 by half the
temperature difference between the temperature of the second region
522 and the room temperature Tr, it is possible to acquire the
information on the temperature of a region that has a temperature
equal to or higher than the temperature Tu. That is, according to
the above method (7), it is possible to acquire the information on
the temperature of a region, within the third region 523, which has
a temperature relatively close to the melting point Tm in
particular. This makes it possible to more accurately grasp the
state of the fiber of the bead.
[0145] (8) An additive manufacturing method according to at least
one embodiment of the present disclosure includes the steps of,
irradiating a raw material (raw material powder 30) with a light
beam 65 as an energy beam (irradiation step S30), and determining a
formation status by the method of monitoring an additive
manufacturing process according to any one of the above (1) to (7)
(formation status determination step S40).
[0146] According to the above method (8), since the step (formation
status determination step S40) of determining the formation status
by the method of monitoring an additive manufacturing process
according to any one of the above (1) to (7) is provided, the
quality of the formation status can be determined based on the
cooling rate parameter P indicating the cooling rate Vc of the
upstream region 85. This can improve the quality of the formed
object 15 in additive manufacturing.
[0147] (9) In some embodiments, in the above method (8), when it is
determined that the formation status is defective in the formation
status determination step S40, the irradiation of the light beam 65
is suspended in the irradiation step S30.
[0148] According to the above method (9), it is possible to lower
the temperature of the formed object 15 during shaping by
suspending the irradiation of the light beam 65. This prevents the
cooling rate Vc of the upstream region 85 from being lower than an
appropriate range.
[0149] (10) An apparatus 100 of monitoring an additive
manufacturing process according to at least one embodiment of the
present disclosure includes, an information acquisition unit 50
configured to acquire information on a temperature of a region
(upstream region 85) upstream, in a scanning direction of an light
beam 65, of a melt pool 81 that is formed by irradiating a raw
material (raw material powder 30) with the light beam 65 as the
energy beam, a parameter acquisition unit 110 configured to acquire
a parameter indicating a cooling rate Vc of the upstream region 85
based on the information on the temperature of the upstream region
85, and a determination unit (formation status determination unit
120) configured to determine a formation status based on the
parameter.
[0150] According to the above configuration (10), the information
on the temperature of the upstream region 85 is acquired, and the
parameter indicating the cooling rate Vc of the upstream region 85
is acquired based on the information on the temperature of the
upstream region 85. Therefore, information necessary for
maintaining the cooling rate Vc of the bead 83 within an
appropriate range is obtained. Then, in the formation status
determination unit 120, the quality of the formation status can be
determined based on the parameter. This contributes to improving
the quality of the formed object 15 in additive manufacturing.
[0151] (11) An additive manufacturing apparatus 1 according to at
least one embodiment of the present disclosure includes, an energy
beam irradiation unit (light beam irradiation unit) 9 that can
irradiate the raw material (raw material powder 30) with the light
beam 65 as an energy beam, and the apparatus 100 of monitoring an
additive manufacturing process according to the above configuration
(10).
[0152] According to the above configuration (11), since the
apparatus 100 of monitoring an additive manufacturing process
according to the above configuration (10) is provided, the quality
of the formation status can be determined based on the parameter
indicating the cooling rate Vc of the upstream region 85. This can
improve the quality of the formed object 15 in additive
manufacturing.
[0153] (12) In some embodiments, in the above configuration (11), a
measurement optical system 53 configured to acquire the above
information on the temperature is further provided. The energy beam
irradiation unit 9 includes a generation unit (oscillation device
91) configured to generate the light beam 65 as an energy beam, and
an irradiation optical system 900 configured to irradiate the raw
material (raw material powder 30) with the light beam 65. A part of
the measurement optical system 53 is common to at least a part of
the irradiation optical system 900.
[0154] According to the above configuration (12), it is possible to
suppress complication of the configuration of the optical system in
the additive manufacturing apparatus 1.
[0155] While preferred embodiments of the invention have been
described as above, it is to be understood that variations and
modifications will be apparent to those skilled in the art without
departing from the scope and spirit of the invention. The scope of
the invention, therefore, is to be determined solely by the
following claims.
* * * * *